In the industry of meat stuffing, e.g., Vienna and frankfurter sausages or special stuffings, tubular shirred casings are required to stuff the meat products. Dimensions of these casings vary depending on the particular product and machines used in preparation of the stuffings.
Several decades ago, all sausage casings were of natural origin, and prepared from animal intestines. Thereafter, several types of synthetic tubular casings for sausages were developed. In particular, regenerated cellulose casings are used in most of the sausages made and sold today.
One of the first stages in preparation of sausages, after the meat emulsion has been prepared, is the stuffing of such meat emulsion into the shirred tubular casings. However, before carrying out the stuffing process, it is required that a closure be formed at the end of the casing to avoid loss of the product therefrom. To that effect, several end closures for shirred casings have been suggested.
U.S. Pat. No. 3,274,005 to Alsys suggests using a hook to twist and invert the end of a shirred casing to produce an end closure. U.S. Pat. No. 3,383,222 to Alsys and U.S. Pat. No. 3,892,869 to Sheridan suggest forming an end closure by pulling the end of the casing to form a tab, closing the end temporarily; inserting a plunger to invert the tab; removing the plunger and placing the end in which the tab is inverted against a fixed surface; and inserting a plunger into the casing from the opposite end to compress the inverted tab and form the end closure.
U.S. Pat. Nos. 3,914,447 and 4,070,729 to Tums teach an end closure produced by inserting a rod into a hollow shirred casing without engaging any portion of the casing, and twisting the terminal pleats until a knot is formed, followed by withdrawing the rod from within the knot without disturbing the closure. The references also suggest placing a passage in the end closure that will permit the passage of gases therethrough but will restrain the passage of food emulsion.
U.S. Pat. No. 4,411,048 to Green suggests supporting a shirred casing on a mandrel; using a hook to grab and remove an end portion of the casing from the mandrel; twisting an end to form a knot; inverting the knot into the casing and placing the inverted end against a fixed surface; and compressing against the surface by inserting a plunger through the mandrel.
U.S. Pat. No. 4,536,175 to Arnold suggest a process for forming an end closure by deshirring the terminal pleats of one end of the strand, inverting the deshirred casing into the bore of the strand, and winding the deshirred casing inside the bore into an end-closure plug.